94 850 intermittent starting problem; nothing's helping!

I have read through other postings here, but they don't quite address
my problem, so I'm hoping someone out there can shed some light on
this.

I have a 1994 non-turbo wagon, and over the summer, it began having a
sporadic problem with hot restarts. After running normally, and then
being parked and shut off for anywhere between 3 and 20 minutes, it
will crank but not fire. I will usually have to hold down the starter
for a few minutes and then it will fire right up. Sometimes I try
holding down the accelerator part way, or simply wait a few minutes to
try again. In the last three months, it has begun stalling on occasion
as well.

I have had the fuel pump, fuel relay, main relay, and ignition switch
replaced. My mechanic put a spark tester on the #1 plug, and when the
problem occurred (that is, when it could actually be reproduced in
front of him-- no small dilemma), the plug is firing. So it appears
the problem is on the fuel side. But what is left to do? Yikes, my
car is totally unreliable during a MN winter! Any help is greatly
appreciated.

Sam

 

Have you run the on-board diagnostics tests yet? NO equipment needed!
I'm not near my information on that, so I'll let others tell you how
to do it...really rather simple.

It beats the replace-parts-till-its-fixed routine ( though I'm betting

Ron/Champ 6

1963 8E5 Champ (Champ 6)
1995 VW Passat (Vanilla..yuk)
1994 Volvo 850 (Tilley)
1973 Volvo 1800 ES (Hyacinth Bucket)

 

I think it could be the fueel pressure regulator that is leaking om the
return line.
It will cause the hot start problem since pressure is gone when car has been
standing for a short time, but engine still not cold enough to give cold
start condition for the engine management.

Regards

Per Hauge

 

Hi, Sam:

You didn't mention the ignition coil or wire, which could be the problem if
they are original.

Also, what about the fuel filter? Is it original too? It's easy to
replace, about 30 bucks for the filter. Same for the coil and wire.
Remember, a lot more current is flowing from the coil and thru its wire than
the individual spark plug wires. I would replace the whole set, be sure
that the set has the coil wire, and replace the cap and rotor. You can buy
a kit from IPD for about 80 bucks. Just mark the wires with tape and do one
at a time. Don't let them touch metal, use the plastic wire separators.

Heat can effect electrical wiring, that's why it is not happening with the
cold - my theory at least.

Also, check the air filter and PCV (flame trap).

Jeff

 

I recall having my gas filler cap replaced in the past when I was having
problems.
There was some pressure-related issue that was the source of my problem.
I thought it was a "reach", but it worked.

Hope it helps.

 

I ran the on-board diagnostics today. The eletrical side came up "no
fault detected," but I got three codes on the fuel side:

3-1-4 Camshaft position sensor signal absent or faulty;
2-1-4 RPM sensor signal absent; and finally
3-2-4 ?? This one isn't listed in the Haynes manual. I may have read
it wrong, but I cleared the codes already. I guess the next time it
freaks out I'll check it again.

If something else were going wrong, could it trigger these codes? Or
should I go ahead and replace the Cam and RPM sensors? Any suggestions
where to look for these parts?

Thank you all so much!

Sam

 

The old style cam position sensor on the older 850's was problematic. If
the signal is absent then the car won't start. Usually the a cam sensor
failure will trigger additonal codes if the signal goes missing while
the engine is running. Any cam sensor from later 850's will work fine,
otherwise try a foreign car parts supplier or a dealer.

Bob

 

My factory manual doesn't list 3-2-4 either, so it's probably a
misread. The first two pint to different sensors, and the book didn't
point to anything common between them. (Except the ECU, I suppose)

Now, I got the 3-1-4 once when I let the car roll backwards on a hill
while the auto trans was in "D" It stalled, and the engine turned
backwards a bit, which generated the fault.

 

The car stalled again today. I ran the diagnostics again, and got the
same codes. But in my last post, I switched the two sides' codes.
Durr!! The fuel side actually came up without faults, and the
electrical had 3-1-4, 3-2-4, and 2-1-4. 3-2-4 is in the Haynes, and it
means the Cam sensor is absent intermittently.

Both the cam sensor and the RPM sensor seem pretty easy to get at.
Anything in particular I should be aware of if I decide to switch them
out myself?

S

 

Okay, my car stalled again yesterday, and I checked the codes again.
The previously listed codes were backwards-- that is, they were all
electrical side codes, not fuel side. Durr! The fuel side registered
no faults. The fault codes I got on the electrical side were 3-1-4 and
3-2-4. I found the 3-2-4 code in the Haynes manual. It's when the cam
position sensor signal is absent intermittently.

Any advice on replacing the cam position sensor? Things to watch out
for?

You folks have been really helpful. This has been really stressful, at
an already stressful time of the year. Thanks again.

Sam

 

Usually the cam seal is leaking and should be replaced at the same time.
The screws holding in the sensor are torx T40. The engine speed sensor
is usually one of the more reliable electronic parts on the white motors
so I would be reluctant to change it out right away. BTW: 314=cam sensor
absent, 324=cam sensor signal intermittent or faulty, 214=engine speed
sensor (rpm) absent intermittently.

Bob